Vertical spray-type ice making machines are well-known and are used extensively in residential and commercial applications. A typical residential ice-making machine may be sized to fit beneath a standard countertop and often includes options for attaching overlay doors to match the surrounding cabinetry. Behind the door, a foamed, self-contained ice storage bin has space for approximate 20-30 pounds of clear ice cubes. The geometry of the ice cubes is unique to the various ice maker manufacturers; round, square, and sometimes octagonal shapes of various sizes can be created. Virtually clear ice is formed by spraying water upwards towards a freeze plate having a plurality of ice making pockets. A pump motor recirculates the water for a continuous stream throughout the freezing cycle. As the pure water freezes first, the impurities fall back into the recirculating tank. The remaining ice on the freeze plate is of high quality—very pure—and highly desirable for home bars, boutiques, and small commercial applications.
Several key components comprise the automatic ice making machine. The refrigeration system typically includes a compressor, hot gas valve, condenser and fan motor assembly, expansion device, and an evaporator assembly including a freeze plate having copper cups or pockets thermally coupled to a serpentine tube. The components of the refrigeration system are coupled together with tubing charged with a refrigerant. The evaporator pockets are typically coated with electroplated tin to prevent the cups from corroding and to provide a safe, sanitary surface for making ice. The opening of the cups face downward toward the stream of water provided by the water recirculation system. The water system includes a water reservoir, circulation pump, and sprayer assembly for distributing water to the pockets. A control system operates the necessary sequence of components to accomplish the freeze and harvest cycling. The process is continued until the ice bin reaches a desired level. The ice bin level may be detected by a control device such as a thermostatic element tied to a signal relay. When the ice approaches the sensor, a signal is sent to the controller to halt the making of ice until the demand returns. In some cases, an external display is included to show the operating status of the machine, to show when the bin is full, or to allow the end user to diagnose errors or select various operating parameters.
Once the harvest is initiated, the controller deactivates the condensing fan and opens the bypass valve to redirect the hot gas discharged from the compressor directly to the evaporator. As the evaporator warms slowly, the ice partially melts, and the bonds between the ice and the pockets of the freeze plate are broken. A released cube falls down toward an inclined ice slide which guides it obliquely towards the opening of the evaporator housing. Then, by its own weight, the cube falls through a separating device and into the ice storage bin. Within a few minutes, all of the ice releases from the freeze plate. Once the allotted harvest time has completed, the controller restarts the ice making sequence, and the process repeats until the storage bin is full.
Particular attention must be given to the design of the separating device. As is the case with vertical spray type ice machines, water can easily escape from the recirculating system due to the spaces between and around the individual dividers of the separating device. A decrease in water level directly translates to a loss in ice capacity, especially in the case of the aforementioned single-parameter systems; therefore, the sum of the width of the individual dividers must completely span the width of the opening, and the gaps between each divider must be held to a minimum. Another issue is that the dividers must be able to swing freely open for all harvested ice cubes regardless of their weight. This can be particularly challenging in that the flat back side of the conventional divider rests against the ice chute to its rear. During the freeze cycle, the addition of recirculating water between the divider and ice chute often creates a surface tension between the two parts, usually, enough to prevent the divider from opening during the subsequent harvest. This phenomena exists despite absence of flowing water—i.e., the surface tension remains. As a result, the ice cubes have the tendency to build up within the housing and can lead to a much larger failure, such as a block of un-harvestable ice formed over the evaporator. The excess ice significantly lowers the temperature of the refrigerant leaving the evaporator. The liquid refrigerant, which would normally boil off in the evaporator, now has the chance of returning to the compressor and causing permanent damage to the piston-cylinder assembly. Therefore, in order to prevent a myriad unwanted errors, particular care must be given to the design of separating device.
One method chosen to address the aforementioned problems is explained in U.S. Pat. No. 7,444,828, which describes using a plurality of ribs extending vertically off of the ice chute to prevent adhesion between itself and separating device. The space created around the rib reduces the surface tension and allows space for the recirculating water to flow. Another embodiment described includes other special geometry applied to the separator itself, such as vertical ribs or a plurality of convex pieces, to prevent the same. The solution presented merely reduces the possibility of adhesion but ultimately does not eliminate it altogether, especially for small or incomplete batches that occur after random shut-downs of the machine, through the loss of water pressure during a previous fill cycle, or from the build-up of sediment or deposits in the sprayer head nozzle. An improvement would be to prevent contact of the divider with any adjacent component altogether and, yet, still achieve the ultimate goal of water retention. Any alternative solution must prove to reliably harvest ice cubes of all sizes; it must allow the free swinging of individual dividers with respect to one another; it must prevent water from escaping between the curtains by adhering to tight tolerances; and, therefore, must be a completely unique solution to what is described in the prior art.